You mean a tandem axle cab and chassis? 10 tires? That's really a 6 wheel, but unless it's 6x6, it matters little.
OK, cab over? Conventional?
C series with 534 would have to be C900 I think. They went up the scale, according to a post here that I am too lazy to look for. 700s got the 401, 800s the 477, 900 the 534---MAYBE. I could be full of beans. But there should be an emblem on the cab, or, the first part of the VIN will tell the tale.
Conventional would be F series, or possibly designated "T" series, for "tandem axle". Again, a 900 methinks.
Tall cabover? Maybe an N series.
Check out these threads...these things are obsolete and not impossible to find parts for, but might be an challenge.
If you are going to put it to work, I'd think twice, three times, how ever many times I had to think about a newer diesel powered truck.
Highway tractors are generally referred to as 18 wheelers because there are 18 tires on 5 axel (including trailer) so I assume you have three axel or a tandem axel truck. If the cab tilts then the truck would be a C series and when there is tandem axel then it is a CT series. A regular cab would be F series with FT for tandem axel. If the truck is a highway tractor then it could be a L, LT, LN, LNT series truck. If still present there should be a tag on the drivers door near the latch and the first letter/letters would identify the series.
These trucks are not known as speed demons but they are known as power houses. There fuel consumption is quite legendary. So the question is how you plan on using the truck.